Development of Methods for Route Optimization of Work in Inhomogeneous Radiation Fields to Minimize the Dose Load of Personnel

The importance of the optimization principle implementation in ensuring the radiation protection of NPP personnel was emphasized. The potential of route optimization in reducing the dose load of the personnel of nuclear power plants and other nuclear facilities is shown. The paper considers the main directions of the authors’ development of the theory and algorithms of route optimization of work in inhomogeneous radiation fields during maintenance, repair, modernization, dismantling of NPP equipment, and elimination of the radiation accident consequences. The results of the computational experiments that were carried out with the “Uran” supercomputer of the IMM UB RAS for the checking of the developed algorithms are presented. The article provides an overview of the developed methods of route optimization of work using the dynamic programming method, including consideration of the constraints in the form of precedence conditions, which means the requirement to perform certain tasks only after the completion of others. Dijkstra’s method was used to solve the “dosimetrist’s problem”, where the optimal route for the dosimetrist’s movement is being constructed, including obstacles bypassing and visiting specified points in the room where it is necessary to perform work to determine the radiation environment characteristics such as measuring the radiation dose rate, taking samples, etc. The routing of movements with the non-additive aggregation of costs is considered. The content of the problem is shown on the example of the radiation accident consequences eliminating on a locality, where, as a result of radioactive fragments scattering, a system of emitting elements appears, which must be deactivated, i.e., dismantled or screened. This task must be carried out in consecutive cycles with a definite threshold level of personnel exposure per shift. A characteristic feature is the dependence of cost functions (here, dosimetric cost) on the list of tasks: only sources that have not been dismantled yet continue emitting at the moment. Precedence conditions are also possible.